1. Field of the Invention
This invention relates to a thin-film magnetic head and a method of making the same, and more particularly to a thin-film magnetic head comprising accumulated thin films of a magnetic material, a coil conductor and insulating layers wherein said coil conductor is made by an ion etching process, and a method of making the thin-film magnetic head.
2. Description of the Prior Art
Various kinds of magnetic recording and reproducing apparatus which record and reproduce electric signals by use of a magnetic recording medium have heretofore been developed. Accompanying the development of the magnetic recording medium which is made compact in size and has various kinds of shapes, there has been developed a variety of types of magnetic heads adapted to the various magnetic recording media. Particularly, for the magnetic recording medium of the disc shape, e.g. a disc having the recording annular area of the innermost radius of 15 mm and the outermost radius of 20 mm, a very compact magnetic head utilizing a thin film has become frequently used, in view of its required compactness. The thin-film magnetic head is now becoming a popular magnetic head for compact magnetic discs owing to its compactness, and further because of the advantage of being easily adapted to multi-channel recording.
One example of the structure of the thin-film magnetic head is as follows. Firstly, a lower magnetic layer in the shape of a thin film is formed on a substrate. Then, a first insulating layer is formed thereon in the shape of a thin film, and subsequently a coil conductor layer also in the shape of a thin film is formed thereon. The coil conductor layer is made into a pattern layer by use of an ion etching process. After this, a thin film of a second insulating layer is formed on the coil conductor layer. Since the surface of the patterned coil conductor layer is waved or stepped, the surface of the second insulating layer is waved or stepped as well. The waved surface of the second insulating layer will affect the magnetic property of the magnetic layer later disposed thereon, and accordingly, a photoresist layer is provided on the second insulating layer before the magnetic layer is disposed, and the surface of the second insulating layer including the photoresist layer, is subjected to an ion etching process to make the surface of the second insulating layer flat. On the flat surface of the second insulating layer, after ion etching, an upper magnetic layer in the form of a thin film is formed.
In the above-described thin-film magnetic head, however, there arises the problem that the surface of the second insulating layer cannot be made perfectly flat, because the surface of the coil conductor layer, after it has been patterned by the ion etching process, is so waved or stepped. This problem will now be explained in detail referring to FIGS. 4A to 4C.
On a substrate 101 are accumulated thin films of a lower magnetic layer 102, a first insulating layer 103, and a coil conductor layer 104 in this order, and on the coil conductor layer 104 is formed a second insulating layer 105. On the surface of the second insulating layer 105, at the edge of the protruded parts caused by the protruded coil portions of the coil conductor layer 104, V-shaped grooves 105A, as shown in FIG. 4A, are formed. The shape of the V-shaped grooves 105A changes according to the shape of the coil conductor layer 104, the thickness of the second insulating layer 105 and so forth, and accordingly it is difficult to predict the depth or shape thereof and completely remove them by the flattening step, by ion etching, as shown in FIG. 4B. When the upper magnetic layer 106 is formed on the second insulating layer 105 which has such surface irregularities in the form of the V-shaped grooves, the surface of the upper magnetic layer 106 will thus also have grooves as shown in FIG. 4C, the magnetic resistance of the upper magnetic layer 106 is thus substantially increased and the efficiency of the magnetic head is materially lowered.